1. Field of the Invention
The present invention relates to a water base pigment ink for ink-jet recording, an ink-jet recording apparatus which accommodates the same and an ink-jet recording method.
2. Description of the Related Art
In the ink-jet recording system, ink droplets are formed by means of a variety of ink discharge methods including, for example, an electrostatic attraction method, a method in which mechanical vibration or displacement is applied to the ink with a piezoelectric element, and a method in which bubbles are generated by heating the ink to utilize the pressure generated thereby, and all or a part of the ink droplets are adhered to a recording objective such as paper to perform the recording.
Those used as the ink composition to be employed for the ink-jet recording system include those in which a variety of water-soluble dyes or pigments are dissolved or dispersed in liquid media each comprising water or a combination of water and a water-soluble organic solvent. In order to achieve the object of the ink for ink-jet recording, the ink is required to possess optimum performance characteristics, for example, such that neither precipitation nor aggregation is caused even when the ink is not used for a long period of time, no clog-up occurs at the tip of the head of the ink-jet printer and in the ink flow passage, the printing quality is satisfactory, and the weather resistance is excellent.
The dye and the pigment, which are used as the coloring agent for the ink for ink-jet recording, may be compared with each other as follows. That is, the water resistance of the dye is unsatisfactory, because the dye is completely dissolved in the ink medium. The light resistance of the dye is fairly inferior to that of the pigment, in view of the chemical structure of the dye. On the contrary, the pigment is dispersed in the ink medium without being dissolved therein. Therefore, the weather resistance including the water resistance of the pigment is extremely satisfactory. Therefore, in recent years, the changeover is progressively made from the dye ink to the pigment ink for the ink for ink-jet recording.
Nowadays, the printing quality equivalent to that of the photographic image is demanded, in which the sharp edge is obtained, and the feathering and the bleeding are suppressed. A variety of suggestions have been made. Especially, glycol-based butyl ether, which is represented by triethylene glycol monobutyl ether as disclosed, for example, in Japanese Patent Application Laid-open No. 10-95941, is known as the permeating agent for the water base ink to suppress the feathering and the bleeding. The glycol-based butyl ether has faster permeation speed into the paper than, for example, the surfactant which is used as the ordinary permeating agent. Therefore, it is considered that the feathering and the bleeding can be suppressed thereby.
However, when the glycol-based butyl ether is added to the ink in an amount necessary to obtain the effect as described above, the blurring tends to occur on the paper surface, because the surface tension of the ink is lowered as well. Consequently, it has been impossible to assert that the effect to improve the feathering and the bleeding is sufficient.
The present invention has been made in order to solve the problem as described above, an object of which is to provide a water base pigment ink for ink-jet recording with which a printing quality including an extremely high image quality is obtained while suppressing the feathering and the bleeding.
According to a first aspect of the present invention, there is provided an ink for ink-jet recording comprising a water-soluble solvent; a pigment; and a compound represented by the following general formula (1): 
In the formula, AO represents oxyalkylene group, R represents alkyl group, and m and n represent natural numbers, respectively.
The water base pigment ink for ink-jet recording of the present invention contains the compound represented by the general formula (1) described above. The present inventors have found out that when the water base pigment ink for ink-jet recording containing the compound represented by the general formula (1) described above is used, it is possible to obtain a printing quality including an extremely high image quality in which the feathering and the bleeding are remarkably suppressed. Thus, the present invention has been consequently achieved.
According to a second aspect of the present invention, there is provided an ink-jet recording apparatus comprising an ink-jet head; an ink tank which accommodates an ink to be supplied to the ink-jet head; and the ink of the first aspect of the invention which is accommodated in the ink tank. The ink-jet recording apparatus of the present invention accommodates the water base pigment ink of the present invention. Therefore, it is possible to provide the water base pigment ink for ink-jet recording with which the printing quality including the extremely high image quality is obtained while suppressing the feathering and the bleeding. The ink tank may be an ink container fixedly provided in the ink-jet recording apparatus or an ink cartridge which is replaceable.